/// <summary>
/// Configures custom port handling with the help of <see cref="ILookup"/>.
/// </summary>
/// <remarks>
/// When a user interacts with edges and their endpoints,
/// node.Lookup(IPortCandidateProvider) is called for the nodes in that graph,
/// and the framework returns the implementation of IPortCandidateProvider which
/// supplies the list of available ports.
///
/// Instead of the default, we'll register a custom lookup for type IPortCandidateProvider.
///
/// Note: we'll update this method in a future tutorial step to work with folding.
/// </remarks>
private void CustomizePortHandling()
{
// Sets auto cleanup to false, since we don't want to remove unoccupied ports.
Graph.NodeDefaults.Ports.AutoCleanUp = false;
// First we create a GraphDecorator from the IGraph.
// GraphDecorator is a utility class that aids in decorating model items from a graph instance.
// Here, we call NodeDecorator.PortCandidateProviderDecorator
// to access the lookup decorator for ports - the thing we want to change.
// One way to decorate the graph is to use the factory design pattern.
// We set the factory to a lambda expression which
// returns instances that implement the IPortCandidateProvider interface.
// Here we can create a CompositePortCandidateProvider that combines various port candidate providers.
// The ExistingPortsCandidateProvider provides port candidates at the locations of the already existing ports.
// The NodeCenterPortCandidateProvider provides a single port candidate at the center of the node.
// The ShapeGeometryPortCandidateProvider provides several port candidates based on the shape of the node.
Graph.GetDecorator().NodeDecorator.PortCandidateProviderDecorator.SetFactory(
node => PortCandidateProviders.Combine(
PortCandidateProviders.FromExistingPorts(node),
PortCandidateProviders.FromNodeCenter(node),
PortCandidateProviders.FromShapeGeometry(node)));
// To modify the existing lookup for a graph element, typically we decorate it with the help
// of one of graph's Get...Decorator() extension methods,
// which allows to dynamically insert custom implementations for the specified types.
// Doing this can be seen as dynamically subclassing
// the class in question (the INode implementation in this case), but only
// for the node instances that live in the graph in question and then
// overriding just their Lookup(Type) method. The only difference to traditional
// subclassing is that you get the "this" passed in as a parameter.
// Doing this more than once is like subclassing more and more, so the order matters.
}
internal CustomPortCandidateProvider(INode node)
{
this.node = node;
geometryPortCandidateProvider =
PortCandidateProviders.Combine(
PortCandidateProviders.FromNodeCenter(node),
PortCandidateProviders.FromShapeGeometry(node));
}
/// <summary>
/// Creates an <see cref="IPortCandidateProvider"/> that considers the node's shape and rotation.
/// </summary>
private static IPortCandidateProvider CreatePortCandidateProvider(INode node)
{
var rotatedPortModel = RotatablePortLocationModelDecorator.Instance;
var freeModel = FreeNodePortLocationModel.Instance;
var rnsd = (RotatableNodeStyleDecorator)node.Style;
var wrapped = rnsd.Wrapped;
var sns = wrapped as ShapeNodeStyle;
if (wrapped is ShinyPlateNodeStyle || wrapped is BevelNodeStyle ||
sns != null && sns.Shape == ShapeNodeShape.RoundRectangle)
{
return(PortCandidateProviders.Combine(
//Take all existing ports - these are assumed to have the correct port location model
PortCandidateProviders.FromUnoccupiedPorts(node),
//Provide explicit candidates - these are all backed by a rotatable port location model
PortCandidateProviders.FromCandidates(
//Port candidates at the corners that are slightly inset
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(freeModel.CreateParameter(new PointD(0, 0), new PointD(5, 5)))),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(freeModel.CreateParameter(new PointD(0, 1), new PointD(5, -5)))),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(freeModel.CreateParameter(new PointD(1, 0), new PointD(-5, 5)))),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(freeModel.CreateParameter(new PointD(1, 1), new PointD(-5, -5)))),
//Port candidates at the sides and the center
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeLeftAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeBottomAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeCenterAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeTopAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeRightAnchored))
)));
}
if (sns != null && sns.Shape == ShapeNodeShape.Rectangle)
{
return(PortCandidateProviders.Combine(
PortCandidateProviders.FromUnoccupiedPorts(node),
PortCandidateProviders.FromCandidates(
//Port candidates at the corners
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeTopLeftAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeTopRightAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeBottomLeftAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeBottomRightAnchored)),
//Port candidates at the sides and the center
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeLeftAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeBottomAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeCenterAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeTopAnchored)),
new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(FreeNodePortLocationModel.NodeRightAnchored))
)));
}
if (sns != null)
{
// Can be an arbitrary shape. First create a dummy node that is not rotated
var dummyNode = new SimpleNode
{
Style = sns,
Layout = node.Layout
};
var shapeProvider = PortCandidateProviders.FromShapeGeometry(dummyNode, 0);
var shapeCandidates = shapeProvider.GetTargetPortCandidates(null);
var rotatingCandidates =
shapeCandidates.Select(c => new DefaultPortCandidate(node, rotatedPortModel.CreateWrappingParameter(c.LocationParameter)));
return(PortCandidateProviders.Combine(
PortCandidateProviders.FromUnoccupiedPorts(node),
PortCandidateProviders.FromCandidates(rotatingCandidates)));
}
return(null);
}
